First, all of the OC fates, baring the Tower, can be done as solo dps without dying so long as you don't get hit by unnecessary damage. It is not the content's fault that you don't switch Phantom Jobs for the few fates with higher incoming damage (maybe like 3 of them), that you don't know how to use personal shields and mits, or that you don't have Bloodbath bound to your bar.

And by "you," I mean the general you. I'm not speaking to anyone specifically.

2nd, just make a party or join a party. The "MM" part of "MMO" stands for massively multi-player. I can personally guarantee that, if you say "LFP," you'll get a party invite most of the time. And the majority of the time, you'll either have a healer or someone with a Phantom job that can heal. It's really, really not the game's fault when someone refuses to party up when the option is available.